21650051 has 4 divisors (see below), whose sum is σ = 21893400. Its totient is φ = 21406704.

The previous prime is 21650021. The next prime is 21650087. The reversal of 21650051 is 15005612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21650051 - 2²² = 17455747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21650011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121541 + ... + 121718.

It is an arithmetic number, because the mean of its divisors is an integer number (5473350).

Almost surely, 2^21650051 is an apocalyptic number.

21650051 is a deficient number, since it is larger than the sum of its proper divisors (243349).

21650051 is an equidigital number, since it uses as much as digits as its factorization.

21650051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243348.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 21650051 is about 4652.9615300365. The cubic root of 21650051 is about 278.7102716410.

Adding to 21650051 its reverse (15005612), we get a palindrome (36655663).

The spelling of 21650051 in words is "twenty-one million, six hundred fifty thousand, fifty-one".